Flat roofing in Winterborne Kingston

Extensions and garden rooms. Where the deck is sound we take it back to boards and lay EPDM rubber, which goes down as a single sheet with bonded seams, or GRP fibreglass where there are kerbs, a step in the level or an awkward corner, since it is laid wet and forms the upstands and edge trim in one piece. Single ply, welded at the laps, is the answer where the area is large.

Garages, stores and converted outbuildings. Usually three layer built up felt beneath a mineral cap sheet, often original and now brittle. A modern torch on system on a dry deck is a good answer on a plain span. A converted outbuilding is the one to look at carefully, because a building that used to be cold and draughty is now heated, and a covering that coped before may be sitting over a build up that cannot handle the moisture.

The deck and the build up. Plywood, OSB or chipboard on joists, with firrings creating the falls. Wet chipboard swells, loses its grip and comes off. Build it warm and the PIR sits on top of the boards over a vapour control layer, so nothing structural is ever cold enough to reach the dew point. Build it cold and the insulation drops between the joists with a ventilated gap above, and the moment that gap is blocked you get condensation and interstitial damp spoiling the decking with no rain involved. BS 6229 covers both, and tapered insulation is how a fall gets corrected where the joists cannot be raised.

Where the water goes. This is the part that gets skipped. A flat roof drains to one or two points, so everything arrives at the rainwater outlet, the hopper below it, the gutter and the downpipe. Block one and you have ponding and standing water sitting over every lap and seam within a day. We check the outlet is the right size, that it is not choked, and that the downpipe below it is actually discharging somewhere, not into a gully that has silted up.

Junctions, openings and the usual repairs. Against brickwork the flashing is chased in and dressed down in lead, never smeared along the joint with mastic, and a parapet has its coping and cavity tray looked at. At the perimeter, the edge trim, the drip and the apron. A rooflight, a lantern or a Velux sits on a formed kerb, as does any soil pipe or vent pipe. Day to day the repairs are blisters and bubbles, a split or crack, and a lifted or failed seam.

No rate per square metre, because the square metres are the easy part and what is under the covering is what decides the job.

Getting to it. A cottage extension with a gate too narrow for a barrow, a garage on a village lane and an outbuilding in a paddock are three different jobs, and the access is what varies most. A garage or a single storey extension will often come off a tower, anything above a two storey wall wants a scaffold, and the platform has to stand while the deck is open rather than for an afternoon. The work at height rules are why it is a priced line rather than something folded into a rate.

The deck under the covering. A sound deck can be re-covered. Chipboard that has been wet for years, or ply that gives underfoot, has to come off and be replaced, and you cannot tell which you have from the ground or from a photograph. We lift a corner before quoting, because the deck is the single biggest swing in the price.

The falls, and where the water is meant to go. Most flat roofs that fail were never laid to a fall, or the fall runs at an outlet that has since been blocked or built over. Correcting it with firrings is more work than laying a membrane and it is the difference between a roof that lasts and one that ponds. Upstands, edge trims and each outlet are priced one at a time, because that is where the hours and the leaks both are.

Comparing quotes? Ask which system is being quoted and how many layers, whether the deck is being renewed or covered over, whether the falls are being corrected with firrings, how the upstands, outlets and edge trims are detailed, and whether the scaffold and the skip are in the price. Two quotes for the same job are usually two different jobs.

We cover Winterborne Kingston, Winterborne Whitechurch, Bere Regis and the DT11 addresses along the valley, with Dorset Council as the planning authority. You are dealing with Bournemouth Roofing & Building, the trading name of Bournemouth Roofing & Building Ltd, registered in England and Wales, company number 15471719, which you can look up in a minute. Thomas Hannen's business, and he is the one who comes out to price the job, not a salesman. A verified customer's 10 out of 10 on Checkatrade. The visit and the written quote are both free.